1. Field of the Invention
The invention relates in general to a folding emergency escape ladder and in particular to a folding emergency escape ladder having attachment means for permanent affixing/attachment to a window sill, a retention means for securing the ladder in the folded position, and a multiplicity of swivel link means for joining the ladder sections.
2. Description of the Related Art
Emergency escape steps or ladders are installed in general on commercial buildings as a matter of course, usually, if not exclusively, required by building codes. Often these escape steps include a collapsible ladder portion or other means of having at least a retractable or collapsible bottom portion to deter unauthorized use. Municipal building codes do not require emergency escape means, and consequently, they are not to be found on residential units. Residential homes above one story, and certainly above two stories, however, do often have the need for an emergency escape route when a fire, earthquake, or other emergency trap the inhabitants in a location above the first floor. A leap from even the second floor can result in serious injury. Several problems with available foldable emergency escapes make residential use unpopular. These problems largely fall into the categories of attachment means for permanently affixing the ladder, retention means for securing the ladder in the folded position, and inexpensive joint means for attaching sections of the ladder to one another.
The various collapsible emergency escape ladders disclosed in he prior art can be generally categorized as (i) portable escape ladders or (ii) permanently affixed escape ladders:
U.S. Pat. No. 3,946,834 is one example of (i) in that it is a self-storing, portable fire escape ladder that includes an enlarged hook means for engaging a window sill or similar structure during use. This type of portable ladder is not suitable for use in a residential emergency because without sufficient practice, high stress and panic due to the emergency would interfere with correct deployment of the ladder such that it securely affixes to the window sill. Another drawback of this design of a portable emergency escape ladder is the complicated arrangement of pivotably interconnected rung ladder sections, whose arrangement is costly for residential use.
U.S. Pat. No. 5,022,491 is one example of (ii) in that it is a permanently affixed escape ladder that includes an exit platform having an exit opening formed at the distal end of the platform to facilitate safe access to the unfolded ladder sections. This patent also includes a plurality of folding ladder sections that are retained in the folded position by a retractable ladder retention means that slidably engages retention posts fixedly attached to the respective ladder sections. Although this ladder is suitable for permanent attachment near an opening in the building unit, the expense of fabrication of the above described beneficial attributes make this incompatible with residential use.